Christine Negroni riffs on aviation and travel and whatever else inspires her to put words to page.

Tuesday, March 12, 2013

B787 Battery Can't Meet 1 In a Billion Standard Experts Say

The Federal Aviation Administrationannounced this afternoon that it has approved Boeing's modified plan to fly the Dreamliner again with its lithium ion batteries on board, the "first step in the process to evaluate the 787's return to flight." The modifications Boeing intends to test include rearranging the internal battery components, improving the insulation of the cells and ... here's the biggie, drum roll please, using a new housing to contain the results of any battery gone haywire and vent overboard the resulting smoke or fumes

Notably absent from the FAA and Boeing statements is the F-Word, that being fire. Despite the fact that the battery gone wild on the Japan Airlines Dreamliner at Boston's Logan Airport did catch fire, there will be no change in the regulator's position that fire on an airplane is a no-no. And that means even if contained in a big strong box, fire will be a no-go on the 787.

The battery from the JAL battery fire in Boston.

"A key feature of the new enclosure is that it ensures that no fire can
develop in the enclosure or in the battery," said a statement from Boeing issued this afternoon. That's all well and good, and certainly speaks to the promise made by the FAA in its interactions with the Air Line Pilots Association back in 2007 when it turned down the pilots' request for fire fighting equipment on Dreamliners by saying, there would be no fire.

Renewing a commitment to separate fire from flight sounds mighty good, but don't get too charged up about it. There are folks who insist, it ain't possible.

"There is zero probability of building a lithium ion battery and promising there won't ever be any chance of fire," said Lewis Larsen, a physicist and the chief executive of Lattice Energy in Chicago. "You cannot honestly say that." Larsen has been studying how microscopically small particles can cause catastrophic failures in lithium ion batteries and he hasn't been quiet about what he has learned. In a paper he posted online in 2010, Larsen wrote,

Exam of JAL battery from NTSB investigation

"A battery pack may well be perfectly safe during the first months of ordinary use; however, dendrites and other types of nanoparticulate structures grow inside over time, increasing the probability of dangerous internal electrical shorts as the battery ‘ages’. The problem is that nobody in the world has any real working experience with large multi-cell Lithium-based battery packs that have endured hard usage and vibration for periods of many years."

An NTSB investigator examines material from the JAL 787

What Larsen and other scientists looking into this issue have found goes beyond dendrites to include unpredictable problems called "field failures" that can occur at a rate of from 1 in 4 to 5 million to one in a million per cell. These failures are "insidious" and "self-driven" according to Brian Barnett, author of a chapter on lithium ion battery safety in the Encyclopedia of Sustainability Science and Technology, and "cannot be protected against by typical safety protection devices."

The battery from ANA's Dreamliner

Over at the National Transportation Safety Board, where the investigation into the JAL Dreamliner battery fire has expanded to include an examination into how the Dreamliner was originally certified, those mysterious field failures have been added to the list of subjects that engineers will be studying I am told.The Dreamliner packs 16 lithium ion battery cells on each plane. I'm no mathematician but with either of the estimated field failure rates cited above, there's no way the Dreamliner can meet the certification standards restricting smoke events to one in every 100 million hours if Larsen and Barnett's numbers are correct. Nor, these scientists say, can a lithium ion battery user ever entirely rule out fire from field failures. Boeing determined that fire in the battery would be a one in a billion catastrophic event in applying for certification for the 787.

In making the announcement, Transportation Secretary Ray LaHood repeated for the umpteenth time the promise of federal safety officials, "We won't allow the plane to return to service unless we're satisfied that the new design ensures the safety of the aircraft and its passengers." Secretary LaHood doth not protest too much. He's clearly trying to live down his statement on January 11th that the Dreamliner is safe to fly.

No one doubts that the Dreamliner has lived up to its billing as a revolutionary airplane. But by hitching their airplane of tomorrow to a complicated and volatile technology Boeing's battery design may be the revolution's first casualty.